#include <iostream>
#include <cmath>
#include <string>
#include <unordered_map>
#include <vector>
#include <algorithm>
using namespace std;

#define _PRIMES {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 431, 433, 439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499, 503, 509, 521, 523, 541, 547, 557, 563, 569, 571, 577, 587, 593, 599, 601, 607, 613, 617, 619, 631, 641, 643, 647, 653, 659, 661, 673, 677, 683, 691, 701, 709, 719, 727, 733, 739, 743, 751, 757, 761, 769, 773, 787, 797, 809, 811, 821, 823, 827, 829, 839, 853, 857, 859, 863, 877, 881, 883, 887, 907, 911, 919, 929, 937, 941, 947, 953, 967, 971, 977, 983, 991, 997, 1009}

template<typename T>
constexpr vector<T> __proxy(initializer_list<T> A) {
    return vector<T>(A);
}

unordered_map<string, short> conv1(
    {
    {"zero", 0},
    {"one", 1},
    {"two", 2},
    {"three", 3},
    {"four", 4},
    {"five", 5},
    {"six", 6},
    {"seven", 7},
    {"eight", 8},
    {"nine", 9}
    }
);

int main() {
    vector<int> primes = __proxy(_PRIMES);
    string f, s, t;
    try {
        cin >> f;
        if (!conv1.count(f))
            throw logic_error("100");
        cin >> s;
        if (!conv1.count(s))
            throw logic_error("10");
        cin >> t;
        if (!conv1.count(s))
            throw logic_error("1");
        short fi=conv1[f], si=conv1[s], ti=conv1[t];
        short ex = fi*100 + si*10 + ti;
        short i = lower_bound(primes.begin(), primes.end(), ex) - primes.begin();
        if (i > 0) {
            short prev_i = i-1;
            short diff1 = ex - primes[prev_i];
            short diff2 = primes[i] - ex;
            if (diff1 <= diff2)
                cout << primes[prev_i] << endl;
            else
                cout << primes[i] << endl;
        } else {
            cout << primes[i] << endl;
        }
    } catch (...) {
        cout << "Wrong input" << endl;
        return 0;
    }
    return 0;
}
